1. Field of the Invention
The invention relates to a cooling system utilizing a compressor for compressing a refrigerant and a constituent device that constitutes a refrigerant circulation circuit together with the compressor, a control device, and a control program.
2. Description of Related Art
As a cooling system utilizing a refrigerant circulation circuit that circulates a refrigerant, an air conditioning system of an indoor space such as stores, and refrigeration and freezer system that refrigerates and freezes merchandizes within showcases installed at stores have been widely used in the past. The refrigerant circulation circuit utilized in such systems includes a compressor for compressing the refrigerant and a constituent device which is a separate device from the compressor that constitutes the refrigerant circulation circuit together with the compressor. Here, the constituent device is, for example, a heat exchanger of the air conditioning system and a showcase and a condenser of the refrigeration and freezer system.
It is common that the compressor has a sensor for detecting a suction pressure (or suction temperature etc.) of the compressor and the compressor is controlled according to the sensor value outputted by the sensor. Because of this, in a case that an abnormality such as a breakdown occurs to the sensor provided at the compressor, the compressor becomes uncontrollable.
As a technology to handle when an abnormality occurred to the sensor provided at the compressor, a cooling system such as described in Japanese Laid-Open No. 2002-188874 (Claim 1, FIG. 1) was proposed. In particular, at the cooling system described in Japanese Laid-Open No. 2002-188874, total of four sensors, that is, a suction pressure sensor, suction temperature sensor, discharge pressure sensor, and discharge temperature sensor are provided at the compressor.
When an abnormality occurred to one of the above four sensors in the cooling system of Japanese Laid-Open No. 2002-188874, the sensor value of the sensor in which the abnormality occurred is supplemented using the sensor values outputted by the remaining three sensors.
However, because it is necessary that a number of sensors are provided at the compressor in the cooling system of Japanese Laid-Open No. 2002-188874, the size of the compressor system was increased and its control became complex.
Also, the technique described in Japanese Laid-Open No. 2002-188874 cannot be applied to a case in which only one sensor is provided at the compressor, and therefore, in such a case, there was a problem that the operation of the compressor could not be continued appropriately when an abnormality occurred to the sensor provided at the compressor.